Disclaimer: Biased Response. It may be correct, but I'm still biased.
Yes, they all stack together.
Explanation of each bonus.
Let's run over each of sources for the bonus to the check.
1. Disguise skill (+17 Untyped):
The skill check rules state:
Each skill rank grants a +1 bonus on checks made using that skill. When you make a skill check, you roll 1d20 and then add your ranks and the appropriate ability score modifier to the result of this check. If the skill you’re using is a class skill (and you have invested ranks into that skill), you gain a +3 bonus on the check.
- Since you have 8 ranks in the skill, this provides a +8 bonus on disguise skill checks.
- Additionally, it is a class skill for you, so you receive an additional +3, since you have 1 or more ranks in the skill.
- Finally, since charisma is the ability score used for disguise skill checks, you add its modifier as well for an additional +6.
Altogether, this grants you a +17 untyped bonus on disguise skill checks.
You get a +2 bonus on all Bluff and Disguise skill checks. If you have 10 or more ranks in one of these skills, the bonus increases to +4 for that skill.
This provides an additional untyped bonus of +2 to disguise skill checks, and when you put another two ranks into the skill, this bonus will increase to +4.
Currently, this grants a +2 untyped bonus to skill checks.
This kit contains tools like makeup and fake facial hair, and provides a +2 circumstance bonus on Disguise checks. A disguise kit is exhausted after 10 uses.
The disguise kit provides a +2 circumstance bonus to your disguise check.
4. Change Shape (+10 racial):
Change Shape (Su) A kitsune can assume the appearance of a specific single human form of the same sex. The kitsune always takes this specific form when she uses this ability. A kitsune in human form cannot use her bite attack, but gains a +10 racial bonus on Disguise checks made to appear human. Changing shape is a standard action. This ability otherwise functions as alter self, except that the kitsune does not adjust her ability scores and can remain in this form indefinitely.
This ability grants you a +10 racial bonus on disguise skill checks to appear human.
First we look at change shape again:
This ability otherwise functions as alter self, except that the kitsune does not adjust her ability scores and can remain in this form indefinitely.
Alter Self is a Polmorph subschool spell, the polymorph subschool says:
Polymorph: a polymorph spell transforms your physical body to take on the shape of another creature. While these spells make you appear to be the creature, granting you a +10 bonus on Disguise skill checks, they do not grant you all of the abilities and powers of the creature. ...
Thus giving a +10 untyped bonus when we use Change Shape.
Benefit: You can precisely mimic the physical features of any individual you have encountered. When you use your racial change shape ability, you can attempt to take the form of an individual, granting you a +10 circumstance bonus on Disguise checks made to fool others with your impersonation.
Realistic likeness grants a +10 circumstance bonus to appear as a specific creature.
Disclaimer: take caution when choosing a person, as you may encounter them, or they could be wanted in the area you're in (or have other issues).
Summary of the bonus stacking.
The rules for stacking bonuses state:
Bonuses are numerical values that are added to checks and statistical scores. Most bonuses have a type, and as a general rule, bonuses of the same type are not cumulative (do not “stack”)—only the greater bonus granted applies.
The important aspect of bonus types is that two bonuses of the same type don’t generally stack. With the exception of dodge bonuses, most circumstance bonuses, and racial bonuses, only the better bonus of a given type works. Bonuses without a type always stack, unless they are from the same source.
Looking over the list of sources for bonuses,we have:
- Disguise skill: +17 (Untyped)
- Deceitful: +2 (Untyped)
- Disguise Kit: +2 (Cirumstance)
- Change Shape: +10 (Racial)
- Only applies to checks to appear as human.
- Polymorph Subschool: +10 (Untyped)
- Realistic Likeness: +10 (Cirumstance)
- Only applies to checks to appear as a specific person.
Note: The circumstance bonus from Realistic Likeness and the Disguise Kit, may be ruled as not stacking by the GM (since only most circumstance bonuses stack), and thus you would only gain a maximum bonus of +49. This may affect the cases given below.
There are a couple cases to consider when applying these bonuses.
You use change shape to turn into your natural human form as Kitsune.
In this case, you are not using realistic likeness to assume the form of someone you have encountered, and thus lose out on the +10 circumstance bonus from realist likeness. Overall, you only receive a +41 to your disguise skill check. The horror.
You use Change Shape to turn into a human you've encountered during your travels.
In this case you get the full +51 bonus to disguise skill checks. Standard realistic likeness disclaimer applies.
You use Change Shape to turn into a non-human you've encountered during your travels.
In this case, you lose out on the +10 Racial bonus from Change Shape, as you're not appearing as a human. Overall, you only receive a +41 to your disguise skill check. The horror. Standard realistic likeness disclaimer applies.
Note: On the side note of Disguise Self:
You make yourself—including clothing, armor, weapons, and equipment—look different. You can seem 1 foot shorter or taller, thin, fat, or in between. You cannot change your creature type (although you can appear as another subtype). Otherwise, the extent of the apparent change is up to you. You could add or obscure a minor feature or look like an entirely different person or gender.
The spell does not provide the abilities or mannerisms of the chosen form, nor does it alter the perceived tactile (touch) or audible (sound) properties of you or your equipment. If you use this spell to create a disguise, you get a +10 bonus on the Disguise check. A creature that interacts with the glamer gets a Will save to recognize it as an illusion.
From my reading of it, Disguise Self would stack with Change Shape, potentially getting you a bonus as high as +61, since it is an untyped bonus. However, anyone who interacts with you, such as by shaking hands or bumping into you, would receive a will save to disbelieve the effect, removing the bonus.